Edible collagen films and casings are known in the current meat product manufacturing art, which have come to replace limited traditional animal tripes. In this sense, German Patent DE-642,922 discloses a collagen film manufacturing process.
Generally speaking, collagen casings are made of a number of components, amongst which collagen as such is predominant, but which include a glycerol mixture that proportionally represents close to 17%, a small quantity of Sorbitol, approximately 2%, and water representing approximately 12%.
For some products, such as hams and the like, rather than using traditional tubular casings, films employed are dispensed in reeled fashion which, when in use, are unreeled with their ends overlapping, thereby to encase the meat product to be prepared. This applies especially to cooked hams which are encased in a net which gives the product shape and consistency before being cooked.
The problem with these netted meat products lies in that, after being cooked, the net sticks to the outside of the processed product, and either bits of net stick to the meat product or the net pulls bits off the product on being removed, which product loses material and has its appearance damaged, rendering it inadequate to be sold.
The current advantageous solution of inserting a thin edible collagen film between the meat mass and the net was arrived at in order to prevent these problems, enabling the net to be easily detached from the products. Furthermore, due to the proteic nature of the collagen film, when it undergoes cooking or smoking, the collagen becomes intimately linked to the meat and is almost impossible to identify or detach from the meat mass, since it is transparent and has no taste, forming an oily product. Said collagen film does not stick to the net in which cooking or smoking takes place, and the product therefore has a good appearance after the net is removed, since no surface loss will have ensued on the meat. In addition, with this collagen film in between, the surface of the meat mass is better protected against any damage it might suffer, loss of juices during cooking is reduced and the external appearance of the product thus netted is improved.
The collagen is usually supplied with a continuous length, a width between 300 mm and 600 mm and a thickness between 0.015 and 0.035 mm. Commercial products of these characteristics are sold, for instance, by the firm Naturin GmbH & Co. under the "Coffi" trade mark.
German Patent DE-3,431,521 of the firm NATURIN-WERK BECKER & CO. is known to comprise a cooked meat product manufacturing process and a mechanism to manufacture such cooked and netted meat products. This invention proposes the application on the raw or previously tied pieces of meat of a coating consisting of an edible collagen layer, and a longitudinally and/or transversely elastic mesh or net is arranged upon such coating, and thereafter the meat goes through a cooking process. In order to prevent the collagen film from severing when the mesh or net is applied, this invention makes provision for both layers, i.e. the net and collagen, to be applied simultaneously, thereby preventing the collagen layer from being damaged at that time.
However, although advantageous, because of stresses existing in modernmost production processes, stretching the elements used to a limit, and above all due to the varying performances of the elastic net and the collagen, the films are still rather frequently severed.
Products capable of improving the extensibility conditions of the collagen film to which they are applied have been used in an attempt at solving these severance problems. It has been found that a thicker film does not improve the extensibility characteristics and hence does not prevent severance. Similarly, increasing percentages of plasticizers, such as glycerine, sorbitol and the like, does not yield satisfactory results since the two overlapping contacting sheets stick to each other, though extensibility is improved.
Obtaining a film having improved extensibility characteristics without undesirable side-effects such as sticking, has been approached by adding an oily component to the collagen mass or to the film after extrusion.
Oily components have been used in other applications providing collagen-based products with characteristics differing from the object of the invention. Thus, for instance:
U.S. Pat. No. 3,446,633 claims the use of edible oil in tubular collagen casing production batches to provide the casing with a more translucent character.
U.S. Pat. No. 3,567,467 claims the use of edible oil with an antioxidant in collagen casing treatment baths to allow for a long storage period.
U.S. Pat. No. 3,627,542 claims the use of a softener comprising a monoglyceride or acetylated monoglycerides, applied to casing treatment baths.
U.S. Pat. No. 4,061,787 claims the use of unsaturated fatty acids as tanning or cross-linking agents for collagen casings.
U.S. Pat. No. 4,115,594 claims the use of an additive containing a sorbitan ester and polyoxyethylene before extrusion of the casing in order to obtain a better dispersion of the cellulose fibres used in making casings, and to improve the folding properties.
U.S. Pat. No. 4,117,171 claims the use of polyol esters and fatty acids and mineral oils to improve the tubular casing antiblocking characteristics, preventing their inner walls from sticking in the tanning process undergone in the various baths before drying.
These inventions all relate to the application of various products to tubular casings in an attempt to improve particular characteristics thereof.
They all provide for the use of claimed components in casings which are treated by means of tanning and/or plasticizing baths before drying.
Reference should lastly be made in regard to prior in art, to Canadian Patent CA-1,253,387 which claims the use of collagen sheets soaked in oil and used dry to encase smoked meat products, in contrast to the use of such sheets after being dipped in water, which resulted in a lesser resistance thereof to tear.
The addition of an oily product to a collagen film applied to a meat product having substantial water contents has been found to provide the film with the desired extensibility characteristics, without the adverse effect of reducing its resistance.